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1  Using Arduino / Project Guidance / Re: Two devices one port. on: April 19, 2013, 03:21:07 am
Thanks for your suggestions guys, I have tried SoftwareSerial before, it works, but seems to be a bit heavy on the processing - it slows down some of the other things the device is doing.
2  Using Arduino / Project Guidance / Two devices one port. on: April 18, 2013, 05:53:39 pm
I've been working with a Mega where I've had the luxury of more serial ports than I need. I'm thinking of downgrading to Arduino Uno or even a mini-pro just to save space and free up my mega for new projects.

My question is this, so far I've been using two ports, one for displaying stuff to to the screen (serial.print() etc)  and one for reading in data from a GPS module. Do I really need two ports? The GPS module just vomits out data continuously, I never write to it, I only ever read. The other port is used only for writing to the screen. Is there anything stopping me from splitting the port? just connecting the GPS tx line to the arduino rx line, and leaving the arduino tx line free for writing?

Secondly, I know the serial port is used when uploading sketches to the board, if I connect my GPS module to this port, is the fact that it tends to continuously spew data even without being asked going to effect the arduino during a sketch upload?

Thanks
3  Using Arduino / Sensors / Re: Strain gauge on a chip? on: April 18, 2013, 03:39:49 pm
Thanks, at least that's a damn sight cheaper than many of the options out there.
4  Using Arduino / Sensors / Strain gauge on a chip? on: April 18, 2013, 07:33:14 am
Hi,

I need to incorporate a strain gauge into a project I'm working on.

Strain gauges themselves seem to be quite cheap, but they don't work without an exciter circuit to provide an input signal, and a hi-gain op-amp circuit to turn a minuscule signal into something a microprocessor can read. (all this according to what I've learnt from google in the last 15 minutes)

There are also a bewildering variety of op-amp circuits out there, however what I'm looking for (and can't find) is a simple 'strain gauge on a chip' I can buy. At this stage of my project I'd prefer not to get side-tracked into analogue circuit design unless I have to. Is there really no single chip solution? I can't be the first one to want to measure strain? Even sparkfun don't seem to have a breakout board to help me, and they have a sensor for everything!

Thanks
5  Using Arduino / Displays / Re: ultra light display? on: April 17, 2013, 07:36:48 am
Thanks, that looks ideal, but where did you get the figure for weight from? I can't see it anywhere n the spec. Or have you got one in front of you?

Cheers
6  Using Arduino / Displays / ultra light display? on: April 17, 2013, 05:56:06 am
Hi, I'm looking for an ultra lite weight display for an arduino. I'm currently using a 16*2 LCD (https://www.sparkfun.com/products/9052) which consists of a large chunk of glass which pushes the weight up to over 35 grams.

Anyone know of anything lighter? I don't need anything bigger or better, 16 * 2 characters is plenty, it's just the weight that needs to change. I guess it's likely to be some form of thin film flexible OLED display or something similar, the weight needs to include any chips/controllers required to use it.

any suggestions?

Thanks
7  Using Arduino / Project Guidance / Re: Protection from shock/vibration on: April 17, 2013, 05:42:39 am
Quote
in a centrifuge with a centripetal force of 100g

Thats a lot! I guess that figure refers to the g force at the outer extremities of the centrifuge, would it not be possible to mount the arduino as close as possible to the centre of rotation? that should reduce the actual forces experienced.
8  Using Arduino / Project Guidance / Re: Satellite Comunications on: April 17, 2013, 05:37:02 am
Quote
plan B.  upgrade it to 4G Wimax
Does 4g Wimax work at a greater altitude than 2g? that's the underlying issue. The only reason I'm considering going to satellite is that I know it will work at almost any altitude.

Regards
9  Using Arduino / Programming Questions / Re: Unrecognized internal error on: April 14, 2013, 04:18:33 pm
Quote
I think it would be worth comparing the two versions of avrdude.conf
I've tried playing with the file, but there the changes seem to be non-trivial. The number of errors seem to go up rather than down as I edit!
10  Using Arduino / Programming Questions / Re: Unrecognized internal error on: April 14, 2013, 03:52:12 pm
Ok, finally got it work. I regressed to version 1.0 and the code compiled, uploaded and ran!

it looks like the post about the possible side effects of the --relaxer flag being added from version 1.0.1 onwards was correct.

So, is the --relaxer option user-configurable? Can I run version later versions and disable this, or am I forever stuck at version 1.0?

Thanks
11  Using Arduino / Programming Questions / Re: Unrecognized internal error on: April 14, 2013, 02:39:40 pm
Ok, I’ve googled, I’ve read, I’ve learnt, and I’ve experimented, but still no luck.

Basically it seems this is a known issue, but with no known fix that will work in all occurrences. It seems to effect larger sketches, and those that use interrupts, it’s got something to do with the ‘linker’ (getting well past the borders of my knowledge here) and something to do with the way code gets distributed in memory. Some developers have had success by installing later version of code, re-arranging #include statements, or installing newer version of avr.

Here’s what I’ve tried,

Firstly, I tried altering the order that my libraries are listed in – didn’t make any difference.

Then I re-tested (compiled, uploaded and ran) each of the 30 plus libraries the sketch calls. No problems with any of them.

Then I tried all the later versions up to 1.0.4, all give the same symptoms.

Next, I’ve tried the solution suggested in this thread http://arduino.cc/forum/index.php?topic=140667.0 (basically I added some extra lines to the top of hardware.h) the results started off looking promising, the code compiled without error, claimed to  upload without error, but then the sketch just didn’t run. (I subsequently found other posts suggesting this fix didn’t work)

Then I tried the fix proposed here …http://arduino.cc/forum/index.php/topic,37965.msg281176.html#msg281176 basically this suggested downloading a new version of WinAVR (version 20100110) and moving the file avrdude.conf. I tried this, the code compiles fine, claims to upload (i.e. displays the message ‘Done uploading’) but also displays the error….

Quote
avrdude: Can't find programmer id "wiring"

Valid programmers are:
  c2n232i  = serial port banging, reset=dtr sck=!rts mosi=!txd miso=!cts [C:\all_apps\arduino-1.0.4\hardware/tools/avr/etc/avrdude.conf:876]
  dasa3    = serial port banging, reset=!dtr sck=rts mosi=txd miso=cts [C:\all_apps\arduino-1.0.4\hardware/tools/avr/etc/avrdude.conf:863]
(plus a long list of more valid programmers)

I then tried improvising, and copied over the original version of avrdude.conf (as downloaded with version 1.0.4). This too compiled ok, and claimed to download, but then produced the error…
Quote
error at C:\all_apps\arduino-1.0.4\hardware/tools/avr/etc/avrdude.conf:332 unrecognized character: "w"
I found some other posts suggesting that the error might be related to the addition of the ‘—relaxer’ flag when Arduino was upgraded to 1.0.1, but couldn’t actually find a proposed fix or workaround.
12  Using Arduino / Programming Questions / Unrecognized internal error on: April 13, 2013, 03:05:34 am
Hi,

I've been trying to load a sketch into a mega and have just started to get this error....
Quote
c:/all_apps/arduino-1.0.1/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/lib/avr6/crtm2560.o: In function `__vector_default':
(.vectors+0x7c): relocation truncated to fit: R_AVR_13_PCREL against symbol `__vector_31' defined in .text section in c:/all_apps/arduino-1.0.1/hardware/tools/avr/bin/../lib/gcc/avr/4.3.2/../../../../avr/lib/avr6/crtm2560.o

It doesn't seem to reference any of my code, so I'm assuming it's some internal issue. The following may also be pertinent...
I'm using version arduino 1.0.1 on windows XP
I'm uploading to a Mega.
As far as I can see all my other sketches will compile and run just fine.
I've dug out some of my old backups of the sketch from several months ago, and they too generate this error. (but I'll swear they worked fine at the time)
I've NOT included any code with this post because 1) it includes a couple of dozen libraries and is quite long, and 2) the error message doesn't appear to reference any of my own code.
I've tried re-installing and re-booting.
Each of the included libraries have a test sketch to go with them, for all of my recently changed libraries I've managed to re-compile and re-test without problems.

Please help, I don't have much hair left and can't afford to rip any more out!

Thanks
13  Using Arduino / Project Guidance / Re: Code management - how to work with multiple versions of the same libraries on: April 05, 2013, 06:55:23 am
Quote
CVS is reasonably easy
Thanks, this isn't one I've reviewed yet, I'll check it out.
14  Using Arduino / Project Guidance / Re: Autonomous boat ferry. on: April 05, 2013, 06:53:17 am
Quote
Also, what if the battery on the boat dies while on the mainland side?
Both sides have power.

Quote
I suppose an emergency inflatable raft kept on the island would take care of that.
They have canoes.

Quote
A directional antenna and 2.4GHz would help be able to control the boat remotely
The intention is that the controller would be mounted on the boat, not on the shore.

Quote
pulse the lights at some frequency, say 1KHz
Good idea, but shouldn't be required. Don't think there are any other light sources in the vicinity.
15  Using Arduino / Project Guidance / Re: Autonomous boat ferry. on: April 05, 2013, 06:23:30 am
Quote
I would go with three light beacons. A triangle is always going to be more accurate.
Good point, didn't think of that, two lights one above the other would be subject to errors when the boat rocks from side to side.
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